Getting swamped: Australian swamp stonecrop (Crassula helmsii) in the UK

In January this year, large parts of southern Australia were ablaze with fierce bush fires, while most of the UK was covered in snow. Half a world away from each other, and at one point nearly 40ºC apart, there aren’t too many similarities to be drawn between the two locations. And yet, there is a water weed, Crassula helmsii, that survives happily in both extremes – and in the UK, where it has been introduced, this adaptability is proving extremely problematic.

 Crassula helmsii, also known as Australian swamp stonecrop or New Zealand pygmyweed, is a small semi-aquatic plant in the Crassulaceae family. As its common name implies, this low-growing succulent originates from the antipodes, but was introduced to Britain from Tasmania almost 100 years ago. Initially sold by garden and aquatic centres as an oxygenating plant, by the 1950s it had established in the wild, and from there it has spread to numerous ponds, lakes and waterways throughout the UK.

A mat of Crassula helmsii in flower

Invasive species catch a wave

Over two years have now passed since the Tohoku earthquake rent the seafloor 40 miles off the coast of Japan. The 9.03 magnitude quake – the largest in Japan’s history – triggered a staggeringly destructive tsunami which cost the lives of over 15,000 people.

Aside from the human tragedy of the disaster, the tsunami has had another, quite unexpected, effect: the transport of invasive species across the globe.  Plants and animals from the north-west Pacific are now washing up over 8000 miles away on North American beaches, sparking fears that a wave of ecological invasions could be threatening coastal environments the length of the continent.

How have these organisms managed to travel so far? Such was the force of the tsunami as it tore into docks, boats and buildings on the Japanese coast that an estimated 1.5 million tons of debris was washed out to sea. This was not just the usual plastic waste that pollutes the Pacific Ocean; individual blocks of steel and concrete weighing over 100 tons have been sighted drifting off the coast of Hawaii and North America. Flotsam this large provides a substrate for sedentary coastal life and can shield species from the worst of oceanic conditions. Individual species regularly make similar transits attached to the hulls of boats.

However, what has surprised ecologists in this instance is the number of species that are washing up after 15 months adrift. Whilst whole communities are not turning up on American shores – larger and more mobile animals in particular have long since been washed away – species are certainly arriving en masse in North America. For example, a pier from Misawa port in Japan was harbouring over 100 species when it beached in Oregon in June 2012.

A pier from Misawa port, covered in non-native kelp, that washed up in Oregon in June 2012.
Source: Oregon Parks and Recreation Department

New Type of Invasive Whitefly Recorded In South Africa

Reblogged from The Plantwise Blog:

A species of whitefly that transmits cassava mosaic virus has been detected in South Africa for the first time. The whitefly, Bemisia tabaci is a cryptic species complex containing some important agricultural pests and virus vectors. The term ‘cryptic species complex’ means that Bemisia tabaci is considered to be a complex of at least 24 different species that look almost identical but are in fact genetically different.  

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Rhododendron ponticum – much more than just an invasive weed!

Rhododendron ponticum, native to southern Europe and south west Asia was introduced into the UK in the 18th Century. Since then, this plant has grown uncontrollably and is now a common sight throughout western parts of the British Isles in areas such as Cornwall, Wales and parts of Scotland and Ireland. Despite producing an attractive flower in the spring, Rhododendron can have damaging effects on the local environment. By growing rapidly this plant outcompetes native flora, decreases biodiversity and furthermore constitutes a sporulating host for the two devastating pathogens Phytophthora ramorum and Phytophthora kernoviae, meaning these pathogens not only infect but also reproduce on R. ponticum.

A stand of invasive Rhododendron ponticum in Windsor Great Park (Picture copyright CABI).

Research Teams and Scientists Working to Stem Ash Dieback Fungus

Reblogged from The Plantwise Blog:

Researchers are working towards developing a cost effective solution to controlling  Ash Dieback fungal disease, a major threat to 80 million ash trees in the UK. As part of the plan to tackle Ash Dieback and other invasive pests and diseases, the government has formulated a team of ten internationally recognised experts in plant health, forestry and wider related disciplines as part of the Tree Health and Plant Biosecurity Taskforce.

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Asian longhorn beetle – A clear case for early eradication

It was confirmed last month that the first population of the forestry pest, the Asian longhorn beetle (ALB), was found in Kent, UK. Forest Research scientists discovered this damaging native of Japan and China infesting around 20 trees, and are now surveying the area to find out the full extent of the infestation. The establishment of this beetle in the UK could be extremely damaging, costing the timber industry millions of pounds, not to mention habitat loss for native species; there is no question that this pest should be eradicated as soon as possible.

Asian long horn beetle. Copyright Kyle Ramirez

Lantana – a battle not yet over!

I’m really pleased to see a more sensible discussion going on about the realities of invasive species management thanks to the article in Invasive plant News which involved one of our regional Coordinators for Invasives Arne Witt from our CABI Africa Centre.  The crux of the issue was the naïve use of the word eradication when speaking of efforts to control one of the worst weeds in the world, Lantana camara, which no one in their right mind would consider achievable, even in the early days.  More worrying is the emerging trend of publishing negative pieces on invasive management, leaving us with the feeling we should give up and accept what opportunist ecologists now call “novel ecosystems” and their increased productivity.  Little mention is made of the biodiversity reduction which is inherent in such invaded ecosystems and even more frustratingly for me, classical biological control is frequently overlooked.  The acceptance that the situation is unmanageable and we need to move on is not valid as long as biocontrol remains untried.  This echoes the excellent response in Science by our very own Harry Evans and his Brazilian colleague Robert Baretto, to the original “embracing invasives” article where they point out that doing nothing is not an option and the integration of biocontrol in areas of high conservation value such as the Galapagos is crucial.  True, in the case of Lantana, which has been the subject of biocontrol research for over a century, success is not a given.  Mankind and nature’s propensity for creating new forms of the weed has resulted in varieties that are not susceptible to some of our most promising biocontrol agents.  However, on the Galapagos a fungal agent looks likely to be able to provide control without harming the native Lantana sp. but remains unexploited.  When this was proposed, the decision was made to spend most of the flood of available money shooting goats from helicopters. A case of sour grapes on my part or perhaps an opportunity missed?  Either way before anyone declares a lost cause when speaking about invasive species they should first check that sensible goals have been set and secondly that all approaches have been explored.